PRESS BULLETIN No. 112.
florida Agricullural Experlinent Slalon.
THE LOSS OF LIME IN DRAINAGE WATERS.
BY A. W. BLAIR.
Lime in the soil is important for most crops, but it is slowly washed out
by rain and carried off in the drainage.
There are two causes, especially, which tend toward the loss of lime
in drainage waters: bacterial action, and the continued use of sulphate of
LOSS THROUGH BACTERIAL ACTION.
In a former bulletin it was pointed out that carbon dioxide is one of
the end-products of the bacterial decomposition of the organic matter that is in
the soil. Some of this carbon dioxide is taken up (dissolved) by water that
is passing through the soil, and in this way comes in contact with the min-
eral matter of the soil. Water which is thus charged with carbon dioxide
has a decided solvent effect upon the carbonate of lime (limestone) in the
soil. This is well illustrated by the caves and sink holes that are so com-
mon in limestone regions. Here the water charged with carbon dioxide comes
in contact with the limestone rock and dissolves great masses of it, with
the result that underground cavities are left. If these e
the surface and the earth falls in, we then have what
sink holes. If whole masses of limestone can be rem
can readily understand how this process will cause a
that are poorly supplied with carbonate of lime. E
unaided eye, appear to contain no carbonate of lim
more or less of this material. Sometimes the quantity is so small, however,
that it is designated as a "trace." Here, too, the water charged with
carbon dioxide is slowly but constantly washing away the small amount that
is present. The analysis of spring and well waters almost invariably shows
the presence of some lime, which came originally from the soil or the rock.
This process goes on day after day and year after year, with the result
that the aggregate loss is enormous. Another end-product of the bacterial
decomposition of the organic matter of the soil is nitric acid. This acid
reacts with the bases in the soil to form nitrates. As lime usually occurs
along with the other bases, nitrate of lime (calcium nitrate) will be formed.
This is readily soluble in water, and can be taken up by plants; but owing
to its ready solubility much of it leaches out with the drainage waters, and
so a quantity of lime will be lost. These losses, however, are in a measure
unavoidable, since, in order that plant food may be elaborated, the bacteria
March 20, 1909.
must carry on the work of breaking up the organic matter. Care in the man-
agement of the soil will to some extent reduce the losses, but some loss is
LOSS DUE TO SULPHATE OF AMMONIA.
When sulphate of ammonia is used, a chemical change takes place be-
tween this and the carbonate of lime that is in the soil, which results in the
formation of sulphate of lime (gypsum). This is more soluble than the
carbonate, and hence more easily lost by leaching. It was shown, for ex-
ample, at the Rothamsted Experiment Station, England, that when mineral
manures (acid phosphate and potash) only were used, carbonate of lime
was lost at the rate of 880 pounds per acre annually; when minerals and
200 pounds sulphate of ammonia were used, the loss was 1170 pounds; when
400 pounds ammonia salts only were used the loss was 1045 pounds; whdn
farmyard manure only was used the loss was 590 pounds; when mineral
manures and 412 pounds nitrate of soda were used the loss was only 565
pounds. It is thus seen that this loss may be prevented to a considerable
extent by substituting barnyard manure or nitrate of soda for sulphate of
OCCASIONAL APPLICATIONS OF LIME REQUIRED.
On account of the gradual removing of the lime from the surface layers
of the soil in the manner mentioned above, there should be occasional appli-
cations of this material in some form, to replace that which is lost. For
'this purpose finely ground limestone may be used-a ton or more to the
acre-at intervals of two or three years. If occasional liming is required in
southern England where much of the soil has resulted from decomposed
chalk, and where chalk often forms the subsoil, is it Ijneeded
here where we often find only traces of lime? Lin
decay of the organic matter of the soil, in the forr
nitrogen fixation; and in order that these operation
the lime that is lost in drainage waters should be
State papers please copy.